Absorption refrigeration system

ABSTRACT

An absorption refrigeration system which includes a scoop pump having a stationary housing mounting therein a plurality of scoop pumps for circulating absorbent solution through the system. Each of the pumps comprises a rotatable pan having at least one inlet conduit leading thereto and at least one eduction conduit leading therefrom. The pan is divided into a fluid accelerating chamber and a pickup chamber and is provided with fluid acceleration inducing vanes effective to assist the rotation of fluid upon entry to the pan so that it is at substantially the circumferential velocity of the pan, thereby significantly improving pump efficiency.

United States Patent l2/1939 Coons Primary Examiner-Meyer Perlin Assistant Examiner-P. D. Ferguson Anarneys Harry G. Martin, Jr. and J. Raymond Curtin ABSTRACT: An absorption refrigeration system which includes a scoop pump having a stationary housing mounting therein a plurality of scoop pumps for circulating absorbent solution through the system. Each of the pumps comprises a rotatable pan having at least one inlet conduit leading thereto and at least one eduction conduit leading therefrom. The pan is divided into a-fluid accelerating chamber and a pickup chamber and is provided with fluid acceleration inducing vanes effective to assist the rotation of fluid upon entry to the pan so that it is at substantially the circumferential velocity of the pan, thereby significantly improving pump efficiency.

PATENTEUNBV 30 Ian 3. e24, 706

INVENTOR. LOUIS H. LEONARD, JR.

ATTORNEY ABSORPTION REFRIGERATION SYSTEM BACKGROUND OF THE INVENTION This invention relates to absorption refrigeration systems and more particularly to pumps for pumping liquid therein. It is known to employ centrifugal pumps to circulate absorbent solution and refrigerant in absorption refrigeration systems. Centrifugal pumps require that a positive suction head exist in order to force the liquid into the impeller eye to prevent flashing and vapor binding. This requirement of centrifugal pumps adds complexity and size to the absorption machine and limits the application of such pumps thereto.

Accordingly, it has been proposed to circulate absorbent solution in an absorption refrigeration system by using one or more scoop pumps generally taking the form of a closed chamber within which is rotatably mounted a peripherally flanged pan for centrifugally impelling at a high tangential velocity liquid directed into the chamber through an inlet conduit, the liquid which is thus flung outwardly being picked up by a scoop or eduction tube. Scoop pumps have, among their advantages, simplicity of construction and generally will not cavitate significantly even though a relatively small quantity of fluid is fed to them. Further, scoop pumps have the advantage of not requiring a suction head and the ability to pump mixtures of noncondensables and liquids, and can be run with no liquid therein if required, without deleterious results.

However, it is highly desirable in the operation of scoop pumps that the fluid in the rotatable pan reach the full speed of the pan before being scooped therefrom by the eduction orifice. and that turbulence and kinetic energy losses be minimized during rotation of the liquid. One of the serious problems exhibited by prior scoop pumps is that the liquid introduced into the rotating pan fails to reach the speed of the pan before it impinges against the scoop. If the liquid is picked up by the scoopbefore it reaches the velocity of the pan, it does not have sufiicient energy to provide adequate discharge pressure from the pump. If the liquid is not picked up by the scoop, it may be decelerated by impingement against the scoop, or turbulence due to the wake of the scoop, and therefore not reach pan velocity on the next revolution when it is either again decelerated or picked up in a low-energy state.

SUMMARY OF THE INVENTION In accordance with this invention, there is provided an absorption refrigeration machine comprising a generator, a condenser, an evaporator, an absorber, and fluid transfer apparatus taking the form of a stationary housing mounting therewithin one or more scoop pumps. The scoop pump includes a rotatable pan divided into an acceleration chamber and a pickup chamber. The acceleration chamber communicates with an inlet passage which passes liquid thereto, and the pickup chamber contains a stationary eduction passage. A plurality of vanes are secured to the pan to assist in rotating the liquid therein. Passage means are provided between the acceleration chamber and the pickup chamber to forward liquid which is accelerated up to the velocity of the pan into the pickup chamber for passage through the eduction conduit to a desired location. Thus, the liquid is enabled to reach the rotational velocity of the pan before being introduced into the chamber containing the eduction conduit and the desired discharged pressure is achieved.

BRIEF DESCRIPTION OF THE DRAWING The single view is a schematic flow diagram, partially in cross section, of an absorption refrigeration system embodying this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with a preferred embodiment of this invention, there is provided an absorption refrigeration system which utilizes water as a refrigerant and an aqueous solution of lithium bromide as an absorbent. A suitable compound,

such as octyl alcohol (Z-ethyl-n-hexanol), may be added to the solution for heat transfer promotion, and corrosion inhibitors may be used if desired. Strong solution" as referred to herein is a concentrated solution of lithium bromide, which is strong in absorbing power. Weak solution is a dilute solution of lithium bromide which is weak in absorbing power.

Referring now to the drawing, there is shown an absorption refrigeration system comprised of a generator 10, a refrigerant condenser 12, an absorber 14, an evaporator 16, a solution heat exchanger 18, and fluid transfer apparatus designated generally by the legends A-1 and A-2 to denote solution circulation means and refrigerant circulation means respectively. A purge unit 22 may be employed to remove relatively noncondensable vapors from the generator to which they are pumped by apparatus A-l.

Generator 10 comprises a boiler to which weak absorbent solution is directed from heat exchanger 18 through conduit means 24. The solution is boiled in the generator by a heat source such as steam pipe 26 to concentrate the absorbent solution by vaporizing refrigerant therefrom. The refrigerant vapor passes into condenser 12 through passage 28. Other types of well-known boilers or generators employing a combustible gas may be utilized.

Water vapor boiled off from the weak solution in generator 10 is condensed in condenser 12 and the condensate is directed by conduit means 30 and float valve 31 to evaporator 16. A heat exchanger 32 through which a heat transfer medium to be cooled flows, is located in the evaporator. A spray header 34 is also disposed in the evaporator to wet the surfaces of the heat exchanger 32 with liquid refrigerant circulated from the evaporator. Refrigerant in evaporator 16 is evaporated to cool the heat exchange medium passing through heat exchanger 32 and the resulting vapor passes through passage 36 to absorber l4.

Absorbent solution in absorber l4 absorbs water vapor from evaporator 16. Heat exchangers 38 and 40 are connected to a source of cooling medium, such as water, to remove waste heat from the refrigeration cycle. Also, located in the absorber 14 is spray header 42 which serves to wet the surfaces of heat exchanger 38 with strong absorbent solution.

Fluid transfer apparatus A-1 and A-2 may comprise in combination a single unitary stationary hermetic housing 44, although of course separate casings may be provided. The housing 44 is desirably shaped at one end to provide an embossment 46 in which is seated bearing means 48 journalling shaft means 50 also received in bearing means 52 and connected to coupling member 54 of magnetic drive means 56 which is in magnetically inductive relation with matching coupling member 58 connected through stub shaft 60 to motor means 62. A plurality of rotatable channel-shaped pans or troughs 68, and 72 are secured to a central shaft 50 by means of collar members 64 and 66 which are welded to radially extending walls 74 and 67 respectively. Pan 68 has a radially inwardly directed flange 78, pan 70 has a radially inwardly directed flange 80, and pan 72 has a radially inwardly directed flange 108, which, together with partition members 74, 67, define the respective channel-shaped scoop pump pans.

Pan 68 is axially divided by a radially extending partition 82 into an acceleration chamber 69 and a liquid pickup chamber 71. Partition 82 is preferably radially spaced slightly inwardly from annular outer wall 59 of pan 68, or is otherwise provided with suitable apertures adjacent wall 59, in order to provide a fluid passage so that liquid can flow axially along wall 59 from acceleration chamber 69 to fluid pickup chamber 71. Nozzle 88a of stationary inlet passage 88 is positioned within acceleration chamber 69 so as to discharge weak solution from absorber 14 directly therein. A plurality of vanes 73 extend radially inwardly from annular wall 59 in acceleration chamber 69 and a plurality of vanes 75 also extend radially inwardly from wall 59 into chamber 71. A stationary eduction conduit having an eduction orifice 90a is disposed in pickupchamber 71 with the orifice being closely adjacent annular wall 59. Vanes 75 have a notch 77 extending radially outwardly from their inner edge toward wall 59 and may extend to the wall so as to form two sets of axially separated vanes in chamber 71. Notch 77 is axially aligned in chamber 71 with eduction conduit 90 so that the entire chamber, including vanes 75, may rotate about the stationary eduction conduit without engagement therewith.

Similarly, pan 70 is provided with a partition 84 axially dividing it into an acceleration chamber 79 and a liquid pickup chamber 81. Acceleration chamber 79 is provided with vanes 83 and pickup chamber 81 is provided with vanes 85 having a notch axially aligned with eduction conduit 98. As previously explained, a suitable fluid passage is formed in partition 84 to permit the passage of liquid along wall 59 from acceleration chamber 79 to pickup chamber 81 during operation of the scoop pump. lnlet conduit 96 extending from heat exchanger 18 and generator is provided with a stationary inlet orifice 96a disposed so as to discharge strong solution from generator 10 into acceleration chamber 79. Eduction conduit 98 passes liquid through passage 102 to spray header 42 in absorber 14.

Radially inwardly directed partition 110 divides pan 72 into an acceleration chamber 109 and a liquid pickup chamber 111 which is similar to the preceding embodiments. Vanes 113 are provided in acceleration chamber 109 and vanes 115 are provided in pickup chamber 111. A plurality of eduction conduits 116 are disposed in pickup chamber 111 with inlet orifice adjacent wall 106. A corresponding number of notches are formed in vanes 1 extending radially outwardly from the inner edge of the vanes in order to provide clearance to prevent engagement of the eduction conduits with the vanes during rotation of the scoop pump. Any desired number of eduction conduits 116 may terminate in a common header 118 and passage 120 for providing liquid refrigerant to spray header 34 in evaporator 16. lnlet passage 114 is disposed so as to discharge liquid refrigerant into acceleration chamber 109. Suitable cleanup scoops or drain lines, such as scoops 55, may be provided to transfer any liquid in the bottom of housing 59 and 67 to a suitable pump chamber to prevent drag on the pans.

In operation, motor 62 rotates magnetic coupling member 58 which in turn causes rotation of magnetic coupling member 56 on the other side of a nonferromagnetic wall of housing 44. Considering first the operation of the weak solution pump, it will be seen that the weak solution discharged into acceleration chamber 69 is brought up to the rotational speed of the scoop pump pan with the assistance of vanes 73. This liquid having achieved the rotational velocity of the pan passes along wall 59 into liquid pickup chamber 71 where it is impelled into the scooped up by eduction conduit 90 and passes through passage 94, heat exchanger 18, and conduit 24 to generator 10.

The arrangement described assures that the liquid introduced into the acceleration chamber is brought up to the full rotational velocity of the pan prior to being introduced into the pickup chamber. Consequently, when the liquid is scooped up into the eduction conduit, it possesses a relatively high kinetic energy or velocity head which is converted to a pressure head in the eduction conduit. This arrangement overcomes the disadvantage of prior scoop pumps wherein the failure of the liquid to be accelerated to the full rotational velocity of the scoop pump pan results in the liquid having in sufficient energy to provide the desired discharge pressure and the low efficiency of the pump requires an expensive large horsepower motor.

It will also be noted that another of the problems of prior scoop pumps is overcome by the provision of vanes 75 in pickup chamber 71. In prior pumps, the eduction conduit produced a substantial wake or turbulence in the scoop pump pan due to impingement of the rotating body of liquid on the conduit. This impingement caused the liquid to be decelerated and to lose energy which in turn resulted in a lower discharge pressure than desired when the liquid was finally scooped into the eduction conduit. Vanes 75 tend to maintain the liquid in the pickup chamber at the rotational velocity of the scoop pump pan and thus assures that the liquid velocity will be relatively high when it is impelled into the eduction conduit, thereby providing a satisfactory pump discharge pressure.

In view of the foregoing explanation, it will be apparent that the strong solution in pan is likewise accelerated in chamber 79, passed to pickup chamber 81, and impelled at high velocity into eduction conduit 98, from which it is passed into spray header 42 in absorber 14. Likewise, refrigerant introduced into acceleration chamber 109 is brought up to the tangential velocity of the pan and impelled into eduction conduits 116 for discharge through spray header 34 over heat exchanger 32 in evaporator 16. Any number of desired eduction conduits may be provided in the various pickup chambers to suit the particular flow requirements of the system.

The bearings 48 and 52 can be lubricated either by solution or water. Additionally, upon machine shutdown strong and weak solutions drain down from the generator and absorber to interrnix in the bottom of the solution side of the housing 44, to give what is essentially a solution side of intermediate concentration and thereby assuring that solution solidification or crystallization will not take place. In this regard, the rotatable pans 68 and 70 may be equipped with centrifugally closed doors or like devices which open when pan rotation ceases to permit drainage of solution therefrom, thereby achieving the desired solution intermixing. A suitable drain or cleanup scoop may be provided to remove fluid accumulated in the bottom of housing 44. Also, fluid transfer apparatus A-l operates as a flash heat exchanger because the stronger and weak absorbent solutions are exposed to each other therein.

By providing an acceleration chamber separated from a fluid pickup chamber with either or both chambers having radial vanes here therein, there is provided a scoop pump having superior fluid handling properties which is especially adapted for use in an absorption refrigeration system. The fluid acceleration chamber assures that the liquid will reach the rotational velocity of the pan before being introduced into the pickup chamber. The liquid in the pickup chamber therefore initially strikes the eduction orifice at full rotational speed and it' has sufficient kinetic energy to provide the desired discharge pressure. Any liquid in the pickup chamber, which is decelerated by impinging against the eduction conduit or due to the wake of the eduction conduit, is brought back to a relatively high rotational velocity by the assistance of the vanes therein. In addition, the limitations on the capacity of the scoop pump are greatly decreased by the provision of a plurality of eduction orifices in a single pickup chamber wherein required to meet the liquid flow requirements of the absorption refrigeration system. The scoop pump arrangement described herein is especially adapted for use in an absorption refrigeration system wherein its advantage of not requiring a suction head may be utilized to reduce the overall height of the machine and because the scoop pump is inherently capable of pumping slugs of vapor in order to purge the absorber. Furthermore, the scoop pump readily adapts itself to expose the strong solution and weak solution pans to each other so that flash heat exchange takes place therebetween to improve the operating economy of the system.

Various changes and modifications of the apparatus disclosed herein may be effected without departing from the scope of the subjoined claims.

lclaim:

1. An absorption refrigeration system comprising a generator for boiling absorbent solution to concentrate the solution by vaporizing refrigerant therefrom; a condenser for condensing refrigerant vapor formed in the generator; an evaporator for evaporating refrigerant condensed in the condenser to provide refrigeration; an absorber for absorbing refrigerant vapor formed in the evaporator into absorbent solution concentrated in the generator; and a scoop pump for pumping absorbent solution between said absorber and said generator; wherein the improvement comprises said scoop pump having a channel-shaped rotatable pan adapted to contain liquid, said pan comprising an annular outer wall having radially inwardly directed flanges extending therefrom. said pan further comprising a radially extending partition wall secured to said scoop pump pan dividing said pan into a fluid acceleration chamber and a fluid pickup chamber, said chambers lying adjacent each other along the axis of rotation of the pan, inlet passage means extending to said scoop pump for supplying absorbent solution to be pumped to said fluid acceleration chamber, stationary eduction passage means having an eduction orifice extending into said fluid pickup chamber for scooping absorbent solution which is rotated by said scoop pump pan from said pickup chamber and passing it to a desired location; passage means for passing absorbent solution from said fluid acceleration chamber to said fluid pickup chamber during rotation of said pan; a plurality of radially in wardly extending vanes disposed in said scoop pump pan for rotation therewith to assist the rotation of absorbent solution with said pan; and motor means for rotating said scoop pump pan and thereby to impel absorbent solution into said eduction conduit.

2. An absorption refrigeration system as defined in claim 1 in which said scoop pump pan is divided by a radial partition into a plurality of scoop pumps for transferring strong solution from the generator to the absorber and for also transferring weak solution from the absorber to the generator.

3. An absorption refrigeration system as defined in claim 1 wherein both said acceleration chamber and said pickup chamber have said radially extending vanes disposed therein.

4. An absorption refrigeration system as defined in claim 1. said vanes being disposed in said pickup chamber and extending radially inwardly from said annual wall of said pan, said vanes having a radial extent greater than the distance between said eduction orifice and the annular wall of said pan. and said vanes having a notch therein transversely aligned with said eduction conduit to permit rotation of said pan and said vanes without engagement with said eduction conduit.

5. An absorption refrigeration system as defined in claim 1 wherein said radially inwardly extending vanes are disposed in said fluid acceleration chamber and extend axially the entire distance between the radial walls of said fluid acceleration chamber, said vanes cooperating with the passage means for passing absorbent solution from the fluid acceleration chamber to the fluid pickup chamber, so that the fluid passing therethrough is substantially accelerated to the full rotational velocity of the fluid in the pickup chamber prior to entering the pickup chamber. 

1. An absorption refrigeration system comprising a generator for boiling absorbent solution to concentrate the solution by vaporizing refrigerant therefrom; a condenser for condensing refrigerant vapor formed in the generator; an evaporator for evaporating refrigerant condensed in the condenser to provide refrigeration; an absorber for absorbing refrigerant vapor formed in the evaporator into absorbent solution concentrated in the generator; and a scoop pump for pumping absorbent solution between said absorber and said generator; wherein the improvement comprises said scoop pump having a channel-shaped rotatable pan adapted to contain liquid, said pan comprising an annular outer wall having radially inwardly directed flanges extending therefrom, said pan further comprising a radially extending partition wall secured to said scoop pump pan dividing said pan into a fluid acceleration chamber and a fluid pickup chamber, said chambers lying adjacent each other along the axis of rotation of the pan, inlet passage means extending to said scoop pump for supplying absorbent solution to be pumped to said fluid acceleration chamber, stationary eduction passage means having an eduction orifice extending into said fluid pickup chamber for scooping absorbent solution which is rotated by said scoop pump pan from said pickup chamber and passing it to a desired location; passage means for passing absorbent solution from said fluid acceleration chamber to said fluid pickup chamber during rotation of said pan; a plurality of radially inwardly extending vanes disposed in said scoop pump pan for rotation therewith to assist the rotation of absorbent solution with said pan; and motor means for rotating said scoop pump pan and thereby to impel absorbent solution into said eduction conduit.
 2. An absorption refrigeration system as defined in claim 1 in which said scoop pump pan is divided by a radial partition into a plurality of scoop pumps for transferring strong solution from the generator to the absorber and for also transferring weak solution from the absorber to the generator.
 3. An absorption refrigeration system as defined in claim 1 wherein both said acceleration chamber and said pickup chamber have said radially extending vanes disposed therein.
 4. An absorption refrigeration system as defined in claim 1, said vanes being disposed in said pickup chamber and extending radially inwardly from said annular wall of said pan, said vanes having a radial extent greater than the distance between said eduction orifice and the annular wall of said pan, and said vanes having a notch therein transversely aligned with said eduction conduit to permit rotation of said pan and said vanes without engagement with said eduction conduit.
 5. An absorption refrigeration system as defined in claim 1 wherein said radially inwardly extending vanes are disposed in said fluid acceleration chamber and extend axially the entire distance between the radial walls of said fluid acceleration chamber, said vanes cooperating with the passage means for passing absorbent solution from the fluid acceleration chamber to the fluid pickup chamber, so that the fluid passing therethrough is substantially accelerated to the full rotational velocity of the fluid in the pickup chamber prior to entering the pickup chamber. 